The natural history of adolescents with blood pressures at or above the 95th percentile has not been well defined. This proposal is a continuation of a cross-sectional prevalence study initiated in 1976, when 10,641 eighth-grade students were screened for high blood pressure. These students will be re-examined as tenth and twelfth graders. The purpose of this study is: 1) to determine the prevalence of hypertension and cardiovascular changes in an older adolescent population; 2) to determine at what age racial differences in the prevalence of hypertension develop among black, whites, and Mexican-Americans; 3) to determine if exercise conditioning has a beneficial effect on the blood pressures of hypertensive adolescents; 4) to determine if exercise stress testing indicates those prone to develop persistent hypertension; 5) to determine the effectiveness of propranolol treatment in hypertensive adolescents and its subsequent alterations on blood pressure response to exercise stress and echocardiographic findings. The hypertensive adolescents have been individually paired with cohorts having blood pressures below the fiftieth percentile and matched with respect to race, age, sex, and body size. The cohorts selected during the eighth-grade screening program have also had exercise stress testing and echocardiographic evaluation of cardiac hypertrophy and function. Those students found to have persistent hypertension during the tenth-and twelfth-grade years will be re-evaluated using these techniques. The blood pressure and electrocardiographic response to exercise stress testing and the echocardiographic findings wwll provide data to determine changes in prevalence of hypertensive myocardial alterations in older adolescents. The exercise training studies will determine whether physical conditioning effectively reduces elevated pressure in the adolescent population. A large population of hypertensive adolescents has already been identified and had baseline cardiovascular studies. Continuation of this project will provide valuable information on the natural history and response to therapy of early essential hypertension.